Dallas running back DeMarco Murray, left, escapes St. Louis Rams middle linebacker James Laurinaitis for a first down during the first half of an NFL football game Sunday in Arlington. The Cowboys routed the Rams, 31-7.

The Associated Press

ARLINGTON — DeMarco Murray strolled around left end for 14 yards on his first carry. There wasn’t a St. Louis defender near him until the end of a much longer run a few plays later.

The Rams almost looked like they didn’t remember what the Dallas running back did to them in their last meeting.

Murray rushed for 175 yards and a touchdown two years after setting a franchise record against St. Louis as a rookie, and Tony Romo threw for three scores in a 31-7 victory Sunday.

The third-year back had 96 yards rushing to 18 for the entire the St. Louis offense at halftime. His 41-yard run two plays into the third quarter gave him his first 100-yard game in more than a year and set up a touchdown for a 24-0 lead.

Murray probably could have threatened the 253 yards he set against the Rams in 2011, but he was soaking up cheers from the crowd when the huge video board at the Cowboys’ $1.2 billion showplace showed him relaxing on the sideline in the fourth quarter.

“When you get a runner like that going, you can feed on him,” Cowboys coach Jason Garrett said. “He gets a little contagious for everybody. Everybody starts feeling it.”

Sam Bradford, Murray’s old college teammate at Oklahoma, was only feeling pressure.

The Cowboys (2-1) sacked him four times in the first half and had six in total after St. Louis (1-2) hadn’t allowed a sack in four games dating to last season. It was the longest streak for the Rams since John Hadl was under center for a division champion in 1973.

DeMarcus Ware had two sacks and broke Harvey Martin’s 30-year-old franchise record of 114. Then-coach Bill Parcells and owner Jerry Jones used to have fun throwing around bets how many sacks 2005 first-round pick Ware would get.

“I think of it every time I think of his number of sacks,” Jones said. “I can’t say that it is unexpected because of how hard he works, and his talent level, and his competitiveness.”

Romo, who had 210 yards passing, went 2 yards to Dez Bryant for the first Dallas score. He had a pair of 24-yarders in the second half to rookie tight end Gavin Escobar and Dwayne Harris.

When the Rams finally started getting defenders around Murray at the line of scrimmage, Romo found him on the outside for a pair of catches on a drive that ended with a 2-yard run by Murray for a 17-0 lead.

Murray went around left end before extending the ball over the goal line right on the pylon, and there was no review. His last 100-yard game was the 2012 opener, and he was coming off a 25-yard performance in a loss at Kansas City.

“I don’t know that there was anything that stood out to me, other than it was just the same commitment and drive and work ethic he’s shown all year in the offseason and the first two games,” Romo said of Murray, who declined to talk to reporters.

St. Louis avoided the shutout on Bradford’s 4-yard pass to Austin Pettis on fourth down late in third quarter after an interception by rookie safety J.J. Wilcox was wiped out by a roughing-the-passer penalty against Jason Hatcher.

Bradford, who finished 29 of 48 for 240 yards, was hit eight more times in addition to the sacks. The Rams didn’t get a first down until the second quarter.

“In the first half, we just never got anything going, played behind the chains all day,” Bradford said. “Just a very poor performance on our part today.”

The Rams had a chance to stay in the game on the drive after their lone score, but Bradford threw behind Chris Givens on fourth down. Dallas scored three plays later for a 31-7 lead when Romo hit Harris in stride in the back of the end zone.

“We didn’t run it, we didn’t stop the run, we didn’t throw it, we didn’t stop their passing game,” Rams coach Jeff Fisher said. “I did not see this coming.”

Notes: The Cowboys won their first two home games at their new stadium for the first time since it opened in 2009. ... Cowboys WR Miles Austin injured a hamstring and didn’t return. Rams backup DE William Hayes, who had been dealing with a hip problem, came out in the first half because of a knee injury.